Wireless LAN Consortium - UNH InterOperability Laboratory...OFDM Physical Layer Test Suite v1.6 DUT:...

Wireless LAN Consortium OFDM Physical Layer Test Suite v1.6 Report

UNH InterOperability Laboratory — 121 Technology Drive, Suite 2 — Durham, NH 03824 — (603) 862-0090

November 9, 2009 Report Rev. 1.0

Jason Contact Network Switch, Inc 3245 Fantasy Parkway Happville, WZ 94035 Mr. Contact, Enclosed are the results from the OFDM Physical Layer Test Suite testing performed on the:

Network Switch 11a Wireless AP

This testing pertains to a set of standard requirements, put forth in the IEEE Std 802.11™-2007 Edition. The tests performed are part of the OFDM Physical Layer Test Suite v1.6, which is available on the UNH InterOperability Lab’s website:

ftp://ftp.iol.unh.edu/pub/wireless/TestSuites/phy/802.11a_PHY_Test_Suite_v1.6.pdf

Issues Observed While Testing 17.2.3 - OFDM Transmit Spectral Mask - The transmitted spectral mask of the DUT was observed to fall out-side the conformance limits. 17.2.4 - Transmit Center and Symbol Clock Frequency Tolerance - The DUT’s symbol clock error was ob-served to break the conformance limits. 17.2.5 - Transmit Constellation Error - The DUT’s relative constellation RMS error was observed to exceed a data rate dependent values outlined in Table 90. As always, we welcome any comments regarding this Test Suite. If you have any questions about the test proce-dures or results, please contact me via e-mail at [email protected] or by phone at (603) 862-2263.

Regards,

John Q. Tester John Q. Tester

ftp://ftp.iol.unh.edu/pub/wireless/TestSuites/phy/802.11a_PHY_Test_Suite_v1.6.pdf

mailto:[email protected]

OFDM Physical Layer Test Suite v1.6 DUT: Network Switch 11a Wireless AP

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Table 1 - Result Key - The following table contains possible results and their meanings

Result Interpretation PASS The DUT was observed to exhibit conformant behavior. FAIL The DUT was observed to exhibit non-compliant behavior.

PASS with Com-ments

The DUT was observed to exhibit conformant behavior, however additional explanation of the situation is included.

Warning The DUT was observed to exhibit behavior that is not recommended. Refer to

Comments From the observations, a valid pass or fail could not be determined. An additional explana-tion of the situation is included.

Not Applicable The DUT does not support the technology required to perform these tests.

Not Available Due to testing station or time limitations, the tests could not be performed, or were performed in a limited capacity.

Not Tested Not tested due to time constraint of the test period.

Borderline The observed values of the specified parameter are valid at one extreme, and invalid at the other extreme.

Informative Results are for informative purposes only and are not judged on a pass or fail basis.

Table 2 - Setup and Configuration Information

Product Manufacturer Network Switch, Inc. Model 11a Wireless AP Serial Number 37843M MAC Address 00:0G:F2:QZ:7X:03 Hardware Version 7M Firmware Version 2.2.3.1 2004-09-29 Software Version 20040921:074551 Build v.1277 Test System Hardware Vector Signal Analyzer Rohde&Schwarz,FSQ-26,100271/026,4.35 Vector Signal Generator Rohde&Schwarz,SMU200A,1141.2005k02/100077,1.45.2.6-01.10.10 (Release)

Wireless LAN Consortium 2 Report Rev. 1.0

http://www.iol.unh.edu/certifyDoc/


GROUP 1: PLCP Tests

Test # Label Part(s) Result(s) a PASS 17.1.1 - Transmit and Receive Supported Data Rates b PASS

Comments on Test Procedure Purpose: To verify that the device under test (DUT) can operate at all defined mandatory data rates, and any op-tional supported data rates. OFDM stations are required to support three different mandatory data rates. In addition to the mandatory data rates, many optional modulation schemes may be implemented extending the payload data rates. The DUT is configured to operate at all mandatory formats and data is exchanged to verify proper transmission and reception. Likewise, the DUT is also configured for any supported optional formats and transmission and reception is verified. a. The DUT should be capable of transmission and reception at 6, 12, and 24 Mbps data rates. b. The DUT should be capable of transmission and reception at all supported optional data rates. Comments on Test Results a. The DUT was observed to operate at 6, 12, and 24 Mbps data rates. b. The DUT was able to transmit and receive at all optional data rates.



Test # Label Part(s) Result(s) a PASS b PASS c PASS d PASS

17.1.2 – PLCP Header Signal Field Format

e PASS Comments on Test Procedure Purpose: To verify that the device under test (DUT) conforms to the OFDM PLCP SIGNAL field format. During transmissions, OFDM stations are required to include a properly formatted PLCP SIGNAL field following the OFDM training symbols at the beginning of a PPDU. This allows the receiving station to properly identify the encoding of the contained data field of the PPDU, and to determine the number of octet transfers that will be need to occur between the PHY and MAC upon reception. The DUT is configured to transmit data to a link partner, which is then demodulated and decoded at the receiver to verify content of the SIGNAL field. a. The RATE field (bits 0 – 3) should accurately reflect the data rate of the transmitted PSDU according to Table

17-5. b. The Reserved bit (bit 4) should be set to a value of zero. c. The LENGTH field (bits 5 -16) should indicate the number of octets contained in the PSDU requested by the

MAC to transmit. d. The Parity bit (bit 17) should be set to one if the number of ones in bits 0 – 16 (including the parity bit) is an

even number; otherwise, it should be set to zero. e. The TAIL portion (bits 18 – 23) of the frame should consist of all zero values. Comments on Test Results a. The RATE field (bits 0 – 3) of the received PPDU was found to accurately reflect the data rate of the transmit-

ted PSDU. b. The Reserved bit (bit 4) was properly set to zero in all observed PPDUs. c. The LENGTH field (bits 5 – 16) properly indicated the number of octets contained in the PSDU. d. The Parity bit (bit 17) was observed to be properly set to one when the total number of ones in bits 0 – 17 was

an even number, and set to zero when the number of bits was an odd number. e. The TAIL portion (bit 18 – 23) were set to zero values in all observed frames.



GROUP 2: PMD Transmit Tests

Test # Label Part(s) Result(s) 17.2.1 - Operating Channel Capability a PASS Comments on Test Procedure Purpose: To verify that the device under test (DUT) is capable of operating on all defined channels. The defined operating channel requirements for an OFDM device are established by regional and national regula-tory administrations. The DUT must support operation in at least one of the defined frequency bands in at least one defined region. Currently there is one region defined, supporting various channel operating frequency ranges to which a conformant device must adhere if operating in that region. The DUT is configured to transmit traffic (either continuously or in burst mode) on each supported channel to a link partner, which is then demodulated and decoded at the receiver. For each supported regulatory domain, the DUT should be able to operate on all specified channels. Comments on Test Results a. The DUT was observed to support operation in the lower (5.15-5.25GHz), middle (5.25-5.35GHz), and upper

(5.745-5.825GHz) U-NII bands.

Test # Label Part(s) Result(s) 17.2.2 - Transmit Power Level a PASS Comments on Test Procedure Purpose: To verify that the transmit power level of the device under test (DUT) is within the conformance limits. The maximum allowable output power requirements for an OFDM device are established by these regional and na-tional regulatory administrations. Currently, one defined body exists, the United States. The DUT is configured to transmit traffic (either continuously or in burst mode) at 6 Mbps and at maximum output power to a link partner, from which the band-power of the signal is calculated. a. For a given geographic region and operating band, the maximum output power should not exceed the values

specified in Tables I.4. Comments on Test Results

U-NII band (GHz) Power Output Limit Power Output of DUT 5.15-5.25 (lower) 40mW 6.2mW 5.25-5.35 (middle) 200mW 8.3mW

5.725-5.825 (upper) 800mW 14.9mW



Test # Label Part(s) Result(s) 17.2.3 - OFDM Transmit Spectral Mask a FAIL Comments on Test Procedure Purpose: To verify the orthogonal frequency division multiplexing (OFDM) transmit spectrum of the device under test (DUT) is within conformance limits. The transmit spectral mask for OFDM follows the spectral mask limits specified in 17.3.9.2. The DUT is configured to transmit traffic (either continuously or in burst mode) using OFDM modulation at maximum output power for all supported data rates and channels to a link partner, from which the spectral mask is computed. The transmitted spec-tral mask of the DUT should fall within conformance limits. Comments on Test Results a. The transmitted spectral mask of the DUT was observed to fall outside the conformance limits. Please see rep-

resentative plots attached at the end of this report (Figures 1 – 6). On channels 36 and 149, the output failed to have the side lobes attenuated sufficiently to meet the spectral mask when transmitting at BPSK, QPSK, and 16-QAM.



Test # Label Part(s) Result(s) 17.2.4 - Transmit Center and Symbol Clock Frequency Tolerance a FAIL Comments on Test Procedure

Purpose: To verify that the center frequency offset of the device under test (DUT) is within the conformance limits. When the transmit center frequency is offset from the actual channel frequency, the spectrum of the transmit signal falls in the adjacent channels, which causes interference in the adjacent channels. To reduce overlap, the transmitcenter and symbol clock frequency tolerances for OFDM devices operating in the 5GHz band should not exceed +/-20 ppm.

Comments on Test Results

Channel Data Rate (Mbps) Peak Center

Frequency Error (ppm)

Symbol Clock Error (ppm)

36 6 19.48438 9.830000 9 16.81388 8.393875 12 16.54100 19.23263 18 14.36800 (22.09775) 24 14.17300 6.771625 36 14.21425 (105.3450) 48 12.75113 (268.7279) 54 13.68263 5.125875

52 6 18.82663 9.57900

9 18.39988 2.81825 12 17.35188 9.94900 18 16.76725 8.37537 24 16.93425 (21.3586) 36 15.83263 (45.1116) 48 14.95250 (96.5930) 54 14.24900 3.46562

149 6 14.38363 7.875125

9 11.91575 6.553625 12 12.49975 6.837125 18 11.81725 6.370875 24 12.77950 6.399375 36 10.95488 (101.6694) 48 10.26400 (212.0950) 54 10.57700 (259.7408)

a. The DUT’s symbol clock error was observed to break the conformance limits on channel 36 at 18, 36, and 48

Mbps, on channel 52 at 24, 36, and 48 Mbps, and on channel 149 at 36, 48, and 54 Mbps.



Channel Data Rate (Mbps) EVM (dB) EVM (%) 36 6 -22.55154 8.395046

9 -17.653482 14.48427 12 -20.362562 10.71224 18 -19.358548 11.97889 24 -20.329474 10.75153 36 -21.177354 9.782674 48 (-22.456412) (8.48500) 54 (-23.384944) (7.65160)

52 6 -18.68438 12.91259

9 -15.89775 17.61109 12 -17.017572 15.54516 18 -17.36086 14.96301 24 -17.666924 14.46152 36 (-19.715278) (11.51256) 48 (-21.947684) (8.97926) 54 (-23.530738) (7.52752)

149 6 -21.752258 9.17675

9 -16.62155 15.53171 12 -20.020308 11.61492 18 -20.805114 12.05024 24 -18.822936 12.71406 36 -20.577634 10.45788 48 (-22.452276) (8.488106) 54 (-22.800734) (8.165498)

a. The DUT’s relative constellation RMS error was observed to exceed a data rate dependent values outlined in Ta-

ble 90 on channel 36 at 48 and 54 Mbps, channel 52 at 36, 48, and 54 Mbps, and channel 149 at 48 and 54Mbps. Please see representative constellation plots at the end of the report (Figures 7 – 12).

Test # Label Part(s) Result(s) 17.2.5 - Transmit Constellation Error a FAIL Comments on Test Procedure

Purpose: To verify that the relative constellation RMS error of the device under test (DUT) is within the confor-mance limits. The constellation error can be measured directly from determining the error vector magnitude (EVM) of the DUT.EVM is based on the concept that any impaired signal can be represented as the sum of an ideal signal and an errorsignal. Since an error signal cannot be measured directly, test instrumentation determines the error signal by recon-structing the ideal signal based on received data and then subtracting it from the actual signal. The relative constellation RMS error should be averaged over all subcarriers, OFDM frames, and packets, and should not exceeda data rate dependent value outlined in Table 3.

Comments on Test Results



Test # and Label Part(s) Result(s)

a PASS 17.2.6 - Spectral Flatness b PASS

Comments on Test Procedure Purpose: To verify that the transmit spectral flatness of the device under test (DUT) falls within the conformance limits. For 802.11 OFDM devices, the output RF filter at the transmitter should assure that all sub-carriers are transmitted as close to an equivalent energy level as possible. This is formally specified in Clause 17.3.9.6.2, along with the ac-ceptable deviation limits specified below. Spectral flatness should be measured by observing the channel estimation sequence, specifically the long training sequence, where all carriers are present at equal transmit level. a. Spectral Lines from carriers –16 to –1 and +1 to +16 should deviate no more than ±2 dB from their average

energy b. Spectral Lines from carrier –26 to –17 and +17 to +26 should deviate no more than +2/-4dB from their aver-

age energy Comments on Test Results

a - b. The DUT was observed to follow the conformance limits for the transmit spectral flatness. Please see repre-sentative spectral flatness plot at the end of this report (Figure 13).




Figure 1 – OFDM Spectral Mask: Channel 36, 9 Mbps, BPSK constellation

-50 -40 -30 -20 -10 0 10 20 30 40 50-90

-80

-70

-60

-50

-40

-30Spectral Mask - 9Mbs, CH:36

Frequency from Carrier - MHz

Pow

er -

dB



Figure 2 - OFDM Spectral Mask: Channel 36, 12 Mbps, QPSK constellation

-50 -40 -30 -20 -10 0 10 20 30 40 50-90

-80

-70

-60

-50

-40



Pow

er -

dB



Figure 3 - OFDM Spectral Mask: Channel 36, 24 Mbps, 16-QAM constellation

-50 -40 -30 -20 -10 0 10 20 30 40 50-90

-80

-70

-60

-50

-40



Pow

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dB



Figure 4 - OFDM Spectral Mask: Channel 52, 24Mbps, 16-QAM constellation

-50 -40 -30 -20 -10 0 10 20 30 40 50-90

-85

-80

-75

-70

-65

-60

-55

-50



Pow

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dB



Figure 5 - OFDM Spectral Mask: Channel 52, 54Mbps, 64-QAM constellation

-50 -40 -30 -20 -10 0 10 20 30 40 50-90

-85

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-75

-70

-65

-60

-55

-50



Pow

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dB



Figure 6 - OFDM Spectral Mask: Channel 149, 6Mbps, BPSK constellation

-50 -40 -30 -20 -10 0 10 20 30 40 50-90

-80

-70

-60

-50

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-30



Pow

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dB



Figure 7 – BPSK Constellation – Channel 36, 6 Mbps

−2 −1.5 −1 −0.5 0 0.5 1 1.5 2−2

−1.5

−1

−0.5

0

0.5

1

1.5

2I−Q Constellation − Rate = 6 Mbps

MeasuredIdealRange of Worst Case Error



Figure 8 - BPSK Constellation – Channel 36, 9 Mbps

−1.5 −1 −0.5 0 0.5 1 1.5−1.5

−1

−0.5

0

0.5

1

1.5I−Q Constellation − Rate = 9 Mbps




Figure 9 – QPSK Constellation – Channel 52, 12 Mbps

−1.5 −1 −0.5 0 0.5 1 1.5−1.5

−1

−0.5

0

0.5

1





Figure 10 – 16QAM Constellation – Channel 52, 24 Mbps

−1.5 −1 −0.5 0 0.5 1 1.5−1.5

−1

−0.5

0

0.5

1





Figure 11 – 64QAM constellation – Channel 149, 48 Mbps

−1.5 −1 −0.5 0 0.5 1 1.5−1.5

−1

−0.5

0

0.5

1





Figure 12 – 64QAM constellation – Channel 149, 54 Mbps

−1.5 −1 −0.5 0 0.5 1 1.5−1.5

−1

−0.5

0

0.5

1





Figure 13 – Spectral Flatness – Channel 36

−25 −20 −15 −10 −5 0 5 10 15 20 25−6

−5

−4

−3

−2

−1

0

1

2

3Spectral Flatness Test Results − CH:36

SubCarrier Number

Rel

ativ

e P

ower

− d

B

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